Optical scanning observation apparatuses have been conventionally known (see, for example, JP 2013-121455A (PTL 1)). The apparatuses is configured to irradiate laser light emitted from a fiber to form a spot on an observation object, where the tip part of the fiber is caused to vibrate, to thereby spirally scan or raster scan the irradiation position of the laser light. Then, signal light such as transmitted light, reflected light, and fluorescence resulting from the observation object are detected by the light detecting section and converted into an electric signal, which is associated with data on the scanning position at each scan point, to thereby generate image data. An example of such apparatus may include, for example, an optical scanning endoscope apparatus for observing living tissues.